机械合金化Fe0.6Ni0.4体系的结构研究

利用XAFS(X射线吸收精细结构)和XRD(X射线衍射)方法研究了机械合金化Fe0．6Ni0.4系统在制备过程中的晶体结构和Fe原子的局域配位环境。结果表明，球磨5h，样品中Fe、Ni原子开始产生合金化，但仍然为bcc和fcc混合的两种物相；球磨10h后，bcc结构Fe的特征配位峰消失，转化为fcc结构，随着球磨时间的增加，配位无序度逐渐增大；球磨40h后，Fe原子的近邻结构又有新的变化，是由多种物态组成的混合物。     

SR-XRD和EXAFS研究Mn掺杂ZnO薄膜的微观结构

用射频磁控溅射技术在蓝宝石衬底上制备了一组不同衬底温度的Mn掺杂ZnO薄膜。质子激发X射线荧光(PIXE)测量表明,薄膜中仅有含量为5 at.%的Mn,未见其它磁性杂质元素(如Fe、Co、Ni等)。同步辐射X射线衍射(SR-XRD)表明,这些Mn掺杂ZnO薄膜具有纤锌矿ZnO结构。SR-XRD和扩展X射线吸收精细结构谱(EXAFS)分析显示,薄膜中未发现Mn团簇或MnO、MnO2、Mn2O3、Mn3O4等二次相,Mn原子是通过替代Zn原子而进入了ZnO晶格。     

离子注入制备SixMn1-x稀磁半导体的X射线衍射

把1×1016/cm2的200 kev Mn离子注入p型Si单晶(100)片中,在N2气氛下进行600℃、700℃、800℃和900℃退火,制得SixMn1-x稀磁半导体.用同步辐射X射线衍射技术研究样品结构,发现Mn的注入和退火导致了Si结晶颗粒的产生,随退火温度升高,间隙位的Mn原子逐渐减少,替代位的Mn原子增加,同时晶格发生膨胀.间隙位和替代位Mn原子间的相互作用导致样品的铁磁性增强.     

Y2-xSmxW3012（x=0．0～0．4）系列固溶体结构、吸水性能和负热膨胀性能的研究

Y2-xSmxW3012（x=0．0～0．4）样品通过传统固相反应合成，用X射线粉末衍射测定了样品的晶体结构。室温X射线粉末衍射在中国科学院研究生院无机材料实验室的MSAL-XD2X射线粉末衍射仪上进行，     

Fe_（73．5）Cu_1Nb_3Si_（13．5）B_9非晶合金化过程的X射线

采用Ｘ射线衍射和正电子湮没多普勒展宽测量相结合，研究了纳米晶态材料Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｂ９的结构随退火温度的变化。实验结果表明：急冷非品样品在４８０℃开始明显晶化，基体中析出体心立方结构的α－Ｆｅ（Ｓｉ）固溶体。随着退火温度的升高，非晶漫射峰不断减弱，而晶态相的衍射谱逐渐增强。进一步计算对衍射谱的分离，给出了品化分数和非晶相平均原子间距随退火温度的变化规律。正电子湮没实验证实了约５５０℃退火时样品内出现以Ｎｂ、Ｂ原子为主的晶界非晶相，Ｓ参数随退火温度的变化与非晶相平均原子间距随退火温度的变化规律一致。     

层状钙钛矿结构锰氧化物Ca3Mn2O7的高压结构相变

利用金刚石压砧高压装置（DAC），对Ca3Mn2O7的粉末样品进行了高压能散X射线衍射实验。结果表明，由于岩盐层易被压缩，在压力作用下层状钙钛矿结构锰氧化物Ca3Mn2O7的结构不稳定。在0－35GPa压力范围内，Ca3Mo2O7晶体结构发生了两次相变。在1．3GPa左右，由原来的四方相变为正交相，在9．5GPa左右，又由正交相向新的四方相转变。     

~(57)Fe注入铜的穆斯堡尔效应研究(Ⅰ)——注入离子铁的热力学过程

本文描述了对注入剂量为1×10~(16)~(57)Fe at/cm~2的离子注入Cu样品,用内转换电子穆斯堡尔谱研究了过饱和Cu-Fe合金中铁原子的退火行为,观察到γ-Fe相和弧立铁原子转变成α-Fe的过程,得到了被弧立铁原子捕获的空穴(团)的解吸附温度约为300℃,α-Fe相的起始形成温度在440℃以下,α-Fe相的溶解温度和铁原子的体扩散温度在520-600℃。     

Fe73.5Cu1Nb3Si13.5B9非晶合金化过程的X射线衍射和正电子湮没研究

采用Ｘ射线衍射和正电子湮没多普勒展宽测量相结合，研究了纳米晶态材料Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｂ９的结构随退火温度的变化。实验结果表明：急冷非晶样品在４８０℃开始明显晶化，基体中析出体心立方结构的α－Ｆｅ（Ｓｉ）固溶体。随着退火温度的高，非晶漫峰不断减弱，而晶态相的衍射谱逐渐增强。进一步计算对衍射谱的分离，给出了晶化分数和非晶相平均原子间距随退火温度的变化规律。正电子湮没实验证实了约５５０     

NdxEr5-xSi3及DyxEr5-xSi3系列化合物的晶体结构和磁性能

利用X射线粉末衍射仪和超导量子干涉磁强计（SQUID）对RxEr5-xSi3（R=Nd,Dy）系列化合物的晶体结构、相组成及磁性能进行了研究,探讨了替代原子种类和含量对其结构和性能的影响。     

DyxEr5－xSi3系列化合物晶体结构和磁性研究

利用电弧炉制备了DyxEr5－xSi3（x＝0,1,2,3,4,5）系列化合物样品。通过X射线粉末衍射分析和磁性测量研究了Dy替代Er对Er5Si3化合物晶体结构和磁性的影响。结果表明：DyxEr5－xSi3（x＝0,1,2,3,4,5）系列化合物的晶体结构为Mn5Si3型,随着Dy替代量的增加,晶胞体积变大。当0≤x≤2时,样品具有反铁磁性,顺磁居里温度由负值（x＝0）变为正值;而x＝3,4时,样品显现铁磁性,顺磁居里温度均为正值。虽然磁性原子及其相互作用的变化对磁性能影响很大,但所有样品的磁有序转变温度都很好地遵守了DeGennes定律。     

直流X射线模拟电缆X射线响应的可行性

本文对电缆X射线辐照响应的机理和模拟方法进行了研究,分析了电缆直流和脉冲X射线辐照响应的异同。建立了带状电缆X射线辐照响应一维计算模型,该模型包含电缆屏蔽层和介质层间隙、介质层瞬态辐射感应电导率等计算模型,模拟了带状电缆直流和脉冲X射线辐照电流响应。模拟结果表明,在X射线注量相同的条件下,电缆直流和方波脉冲X射线响应具有类似的波形特征及相同的间隙电压。因此,在该计算模型描述的电缆X射线辐照响应机制下,可利用直流X射线开展相应的脉冲X射线辐照响应机制模拟。     

凸度检测系统中X光机参数对厚度测量精度的影响

X射线凸度检测技术可在线获得板带材的断面轮廓并反馈到连轧系统实现实时凸度控制,在冶金工业中得到广泛应用,是冶金自动化中的关键技术。该项技术存在厚度测量范围大、测量精度要求高的特点。本文通过理论分析厚度测量精度与X光机管电压和管电流的关系,得到X光机管电流是决定系统极限测量精度的主要因素,X光机管电压是决定系统测量厚度范围的主要因素。在此基础上给出了由测量精度确定管电流的方法和由测量范围确定管电压的方法,为系统X光机的选型和测量档位设定提供指导依据。     

Apparent Linear Attenuation Coefficients in Phase Contrast X-Ray Tomography

In the inline phase contrast X-ray tomography the reconstructed apparent linear attenuation coefficient values may be greatly larger than sample’s linear attenuation coefficients or even be negative. In this work we present a general formula to quantitatively relate the apparent linear attenuation coefficient values in cone-beam phase contrast tomography to sample’s linear attenuation coefficients and refractive indices. This formula overcomes the gross inaccuracy of the existing formula in the literature in analyzing high-resolution phase contrast tomography, and it will be useful for correctly interpreting and quantifying the apparent linear attenuation coefficients in cone-beam X-ray phase contrast tomography.     

Scanning X-ray microfluorescence in a SEM for the analysis of very thin overlayers

In this paper, we used back-foil scanning X-ray microfluorescence (SXRF) and we examined the sensitivity of the technique for the analysis of very thin overlayers, where electron probe X-ray microanalysis (EPMA) reaches its detection limits. The lateral resolution of back-foil SXRF is also calculated for all the systems used. Both experimental results and Monte-Carlo calculations are used in this respect. Back-foil SXRF used in optimized experimental conditions, is found to be more sensitive than EPMA, especially in the case of very thin overlayers. The lateral resolution of back-foil SXRF is of the order of some micrometers. This is much better than the lateral resolution in conventional XRF and of the same order of magnitude as in EPMA.     

使用X光聚束系统的X射线荧光分析研究

复合光导管组成的Ｘ光透镜可将发散的Ｘ光束聚至直径φ０．５ｍｍ，聚束后的功率密度增加１０＾４倍，这种新型的Ｘ光透镜已用于Ｘ射线荧光分析研究，使用Ｘ光管功率仅２Ｗ，而探测限可达１０＾－９－１０＾１０ｇ．     

X光透镜应用于蛋白大分子晶体衍射

采用Ｘ光透镜替代单色仪双聚焦镜应用于生物蛋白大分子晶体衍射分析,照射晶体样品的光强提高１－２个量级,衍射强度的提高远大于５倍,大大缩短了测试时间,分辨能力改善０．０２－０．０６ｎｍ,信噪比也有改善。     

X光透镜在X射线衍射技术中的应用

用整体平行束X光透镜代替常规衍射仪的索拉狭缝和/或附加狭缝,入射和衍射X光强度可提高1.5―3.5倍,分辨率可达0.4°,可用于薄膜、粉末样品和离子束沉积样品的分析。将微会聚X光透镜应用于生物大分子衍射、高压X射线衍射、四圆X射线衍射3个不同的衍射领域,在相同X光源功率条件下,使用X光透镜后的衍射强度提高到原来的3―10倍,信噪比和分辨率有不同程度的改善。     

Development of a new X-ray source using backscattered X-ray with the use of a cold cathode

The development of an intense X-ray source using backscattered X-ray produced using an advanced electrode configuration is described. The electrodes were composed of field emitters deposited on a wire mounted on a perforated plate as the cathode and a copper plate as the anode. Electrons from these emitters collided with the copper plate and X-ray was generated at collision points. The backscattered X-ray in the direction normal to the electron trajectory through a hole in the anode escaped from the vacuum chamber through a beryllium window. Continuous and characteristic X-rays were detected at an applied voltage lower than that of a conventional X-ray source from 3.0 to 9.4 kV, respectively. Moreover, the X-ray dosage measured with a survey meter reached 0.95 mSv/h at 5.0 kV of applied voltage. The transmission images of three types of material used as an X-ray source for the X-ray imaging system indicate three advantages; low power consumption, focal point controllable by adjusting applied voltage, and photographable motion picture of X-ray transmission.     

Influence of resonant Raman scattering in the elemental analysis using X-ray emission based techniques

A tabulation of characteristic X-ray energies across the periodic table are provided where those X-rays are expected to result in a significant fractional resonant Raman scattering (RRS) contribution to the X-ray attenuation from a particular shell/subshell of the same or another element. The tabulations can be considered as guideline so as to know what can be expected due to RRS in typical photon- and particle-induced X-ray emission spectrometry. The RRS contribution is not included in the available theoretical attenuation coefficients, which are generally used in estimation of the matrix corrections in routine quantitative elemental analysis based on various X-ray emission techniques. The radiative RRS peaks can also interfere with normal X-ray spectrum and influence the elemental analysis. The RRS cross-section depends upon the energy difference of the X-ray energy and the shell/subshell ionization threshold taken in the units of the shell/subshell energy width, density of available states near the Fermi level, and the band structure in case the element is in the solid form. Some aspects of the dependence of the RRS contribution on the chemical forms of the elements are also discussed.     

高能X射线探测器射线串扰模拟研究

探测器的串扰噪声会对探测器的信噪比以及高能工业CT的图像质量产生很大的影响。本文利用EGSnrc程序模拟估算了CdWO4探测器模块的串扰噪声,并初步分析比较了影响探测器模块串扰噪声的各种因素。对在实际中选用和设计探测器模块有一定的指导意义,同时为利用软件修正探测器串扰噪声提供了理论计算参数。